In January 2001, Wirtgen opened discussions with the City of Edmonton to explore the possibility of developing a Cold Foam In Place Recycling project. The City had identified a section of Ellerslie Road that was due for rehabilitation which is a good candidate for a recycling project.
The standard design procedures required for the reworking of the upper base layer with the addition of emulsion. After field investigations (test pits, DCPs, cores and a visual assessment) it was found that the existing road consisted of an asphalt layer on top of a emulsion stabilised base with a binder content of approximately 7%. The high bitumen content in the base layer resulted in a material with little to no fines present, making it impossible to foam stabilize as a minimum of 5% fines are required in the virgin material to effectively disperse the foamed bitumen. Additional material with a high fines content was therefore blended with the in-situ material before foam stabilised.
Severe rutting was noted in isolated sections of the road. To ensure an equal bitumen application to the material is achieved the rutted areas were pre-pulverized to a depth of 100mm. 100mm of the imported material was placed with a paver and then the upper 200mm stabilized with 2.5% foamed bitumen and 1.5% cement. A final 35mm asphalt surfacing layer was then constructed as te final road surface.
Loudon International was involved throughout the project and assisted with the field investigations, the mix design, the construction procedures and ensured the material adhered to the set out specifications.
During the recycling project, The City of Edmonton and Wirtgen held a foam bitumen seminar for 66 Engineers representing local government, private contractors and material engineers. After a presentation of foam bitumen stabilization the guests were invited to the job site where they could see the layer being constructed.
In June 2002, almost 12 months after construction was completed, an inspection was done and no evidence of distress was noted.